Systems and methods herein generally relate to inkjet printers and more particularly to devices and processes that steer sheets and perform jetting of printheads.
On aqueous inkjet printers, various sheet sizes are used for printing jobs. A maximum print zone exists, as limited by the physical footprint of the inkjet printheads. For example, when one is printing legal size documents, long edge feed, with a relatively full image, all jets on the inkjet printheads (e.g., the maximum print zone) could be used. However, if one uses a smaller size sheet or uses a short edge feed, there could be jets that will not experience any ink movement for a particularly long time, and this is dependent on the length of the job being printed.
As a result, unused jets can develop a viscous fluid that blocks the jets, causing missing jets if the next job requires these previously unused jets. Thus, nozzles of inkjet printheads routinely clog when such are unused for extended periods, for example when certain colors or nozzles go unused for an extended period.
This can result in nozzles that do not eject any ink, or that only eject a significantly reduced drop mass, which causes less than optimal pixel placement (“streaky” solid-fill images) and lower than target drop mass (lighter than target solid-densities). To mitigate, users often run print head maintenance processes that jet ink from the heads. However, print head maintenance processes can be a waste of consumables, as well as a productivity detractor.
If the clogged nozzle condition goes uncorrected, it can lead to intermittent firing and the jet can eventually cease firing, and such a situation can be unrecoverable resulting in irreversible printhead damage. Therefore, maintaining clog free printheads provides greater longevity to the inkjet printheads. Depending on the pre-condition of the head, the time scale for onset of such unrecoverable failure could range from a few hours to days.
Additionally, certain colors (e.g., magenta, etc.) are more susceptible to clogging relative to other colors, because certain color inks dry faster than other color inks, which causes the ink to dry in the nozzles of the inkjet printhead during extended inactivity. Such nozzle clogging issues can be mitigated, but not avoided, by jetting and cleaning cycles.